A quick question related to Amperex Bugle Boys

op is inquiring about a 5ar4 / gz34 rectifier, so gm (transconductance) is not a concern

gm levels matter for most tubes that are directly in the signal path (input, driver, buffer, follower, power tubes)... though most traditional testers have severe limitations testing real world performance of power tubes as well, other than most basic function (is it even working or not)

amperex’s ’bugle boys’ was a marketing/sales branding by the amperex company, later bought out by the dutch electronics conglomerate philips, and the underlying tubes could be made in the uk or in holland... both are legit real deal amperex’s - the gz34 rectifiers in the ’60’s and ’70’s were made in blackburn, england and heerleen, netherlands

no you cannot rell the remaining lifespan fom the tested figures... best to look at the condition of the tubes themselves, especially how shiny and new the getter flash is at the top of the tube, and whether there are heat/burn marks elsewhere on the glass envelope